Galectin-1 Couples Glycobiology to Inflammation in Osteoarthritis through the Activation of an NF-κB-Regulated Gene Network

The degenerated glenohumeral joint

Aims

This study aimed to define the histopathology of degenerated humeral head cartilage and synovial inflammation of the glenohumeral joint in patients with omarthrosis (OmA) and cuff tear arthropathy (CTA). Additionally, the potential of immunohistochemical tissue biomarkers in reflecting the degeneration status of humeral head cartilage was evaluated.

Methods

Specimens of the humeral head and synovial tissue from 12 patients with OmA, seven patients with CTA, and four body donors were processed histologically for examination using different histopathological scores. Osteochondral sections were immunohistochemically stained for collagen type I, collagen type II, collagen neoepitope C1,2C, collagen type X, and osteocalcin, prior to semiquantitative analysis. Matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13 levels were analyzed in synovial fluid using enzyme-linked immunosorbent assay (ELISA).

Results

Cartilage degeneration of the humeral head was associated with the histological presentation of: 1) pannus overgrowing the cartilage surface; 2) pores in the subchondral bone plate; and 3) chondrocyte clusters in OmA patients. In contrast, hyperplasia of the synovial lining layer was revealed as a significant indicator of inflammatory processes predominantly in CTA. The abundancy of collagen I, collagen II, and the C1,2C neoepitope correlated significantly with the histopathological degeneration of humeral head cartilage. No evidence for differences in MMP levels between OmA and CTA patients was found.

Conclusion

This study provides a comprehensive histological characterization of humeral cartilage and synovial tissue within the glenohumeral joint, both in normal and diseased states. It highlights synovitis and pannus formation as histopathological hallmarks of OmA and CTA, indicating their roles as drivers of joint inflammation and cartilage degradation, and as targets for therapeutic strategies such as rotator cuff reconstruction and synovectomy.

Baseline levels of circulating galectin-1 associated with radiographic hand but not radiographic knee osteoarthritis at a two-year follow-up

Objective

We tested the potential of circulating galectin-1, interleukin (IL)-1 beta, IL-6, and tumour necrosis factor alpha (TNF alpha) levels at baseline in individuals with knee pain as biomarkers for development of radiographic knee and/or hand osteoarthritis (OA).

Design

This study comprised 212 individuals with knee pain from the Halland osteoarthritis cohort (HALLOA). Clinical characteristics and serum/plasma levels of galectin-1, IL-1 beta, IL-6, and TNF alpha were measured at baseline, and knee and hand radiographs were obtained at a two-year follow-up. The predictive value of circulating inflammatory markers and clinical variables at baseline was assessed using multinominal logistic regression for those who developed radiographic OA in knees only (n ​= ​25), in hands only (n ​= ​40), and in both knees and hands (n ​= ​43); the group who did not develop OA (n ​= ​104) was used as reference. Correlations were assessed using Spearman's correlation coefficients.

Results

As expected, age was identified as a risk factor for having radiographic knee and/or hand OA at the two-year follow-up. Baseline circulating galectin-1 levels did not associate with developing radiographic knee OA but associated with developing radiographic hand OA (odds ratio (OR) for a 20% increased risk: 1.14, 95% confidence interval (CI) 1.01-1.29) and both radiographic knee and hand OA (OR for a 20% increased risk: 1.18, 95% CI 1.05-1.30). However, baseline IL-1 beta, IL-6, and TNF alpha did not associate with developing radiographic knee and/or hand OA.

Conclusion

Non-age adjusted circulating galectin-1 is superior to IL-6, IL-1 beta, and TNF alpha in predicting radiographic hand but not knee OA.

Role and molecular mechanism of ghrelin in degenerative musculoskeletal disorders

Ghrelin is a brain-gut peptide, and the first 28-peptide that was found in the gastric mucosa. It has a growth hormone (GH)-releasing hormone-like effect and can potently promote the release of GH from pituitary GH cells; however, it is unable to stimulate GH synthesis. Therefore, ghrelin is believed to play a role in promoting bone growth and development. The correlation between ghrelin and some degenerative diseases of the musculoskeletal system has been reported recently, and ghrelin may be one of the factors influencing degenerative pathologies, such as osteoporosis, osteoarthritis, sarcopenia and intervertebral disc degeneration. With population ageing, the risk of health problems caused by degenerative diseases of the musculoskeletal system gradually increases. In this article, the roles of ghrelin in musculoskeletal disorders are summarized to reveal the potential effects of ghrelin as a key target in the treatment of related bone and muscle diseases and the need for further research.

Heterologous Interactions with Galectins and Chemokines and Their Functional Consequences

Extra- and intra-cellular activity occurs under the direction of numerous inter-molecular interactions, and in any tissue or cell, molecules are densely packed, thus promoting those molecular interactions. Galectins and chemokines, the focus of this review, are small, protein effector molecules that mediate various cellular functions-in particular, cell adhesion and migration-as well as cell signaling/activation. In the past, researchers have reported that combinations of these (and other) effector molecules act separately, yet sometimes in concert, but nevertheless physically apart and via their individual cell receptors. This view that each effector molecule functions independently of the other limits our thinking about functional versatility and cooperation, and, in turn, ignores the prospect of physiologically important inter-molecular interactions, especially when both molecules are present or co-expressed in the same cellular environment. This review is focused on such protein-protein interactions with chemokines and galectins, the homo- and hetero-oligomeric structures that they can form, and the functional consequences of those paired interactions.

Ensemble learning model for identifying the hallmark genes of NFκB/TNF signaling pathway in cancers

BACKGROUND

The nuclear factor kappa B (NFκB) regulatory pathways downstream of tumor necrosis factor (TNF) play a critical role in carcinogenesis. However, the widespread influence of NFκB in cells can result in off-target effects, making it a challenging therapeutic target. Ensemble learning is a machine learning technique where multiple models are combined to improve the performance and robustness of the prediction. Accordingly, an ensemble learning model could uncover more precise targets within the NFκB/TNF signaling pathway for cancer therapy.

METHODS

In this study, we trained an ensemble learning model on the transcriptome profiles from 16 cancer types in the TCGA database to identify a robust set of genes that are consistently associated with the NFκB/TNF pathway in cancer. Our model uses cancer patients as features to predict the genes involved in the NFκB/TNF signaling pathway and can be adapted to predict the genes for different cancer types by switching the cancer type of patients. We also performed functional analysis, survival analysis, and a case study of triple-negative breast cancer to demonstrate our model's potential in translational cancer medicine.

RESULTS

Our model accurately identified genes regulated by NFκB in response to TNF in cancer patients. The downstream analysis showed that the identified genes are typically involved in the canonical NFκB-regulated pathways, particularly in adaptive immunity, anti-apoptosis, and cellular response to cytokine stimuli. These genes were found to have oncogenic properties and detrimental effects on patient survival. Our model also could distinguish patients with a specific cancer subtype, triple-negative breast cancer (TNBC), which is known to be influenced by NFκB-regulated pathways downstream of TNF. Furthermore, a functional module known as mononuclear cell differentiation was identified that accurately predicts TNBC patients and poor short-term survival in non-TNBC patients, providing a potential avenue for developing precision medicine for cancer subtypes.

CONCLUSIONS

In conclusion, our approach enables the discovery of genes in NFκB-regulated pathways in response to TNF and their relevance to carcinogenesis. We successfully categorized these genes into functional groups, providing valuable insights for discovering more precise and targeted cancer therapeutics.

Galectin-1: A Traditionally Immunosuppressive Protein Displays Context-Dependent Capacities

Galectin–Carbohydrate interactions are indispensable to pathogen recognition and immune response. Galectin-1, a ubiquitously expressed 14-kDa protein with an evolutionarily conserved β-galactoside binding site, translates glycoconjugate recognition into function. That galectin-1 is demonstrated to induce T cell apoptosis has led to substantial attention to the immunosuppressive properties of this protein, such as inducing naive immune cells to suppressive phenotypes, promoting recruitment of immunosuppressing cells as well as impairing functions of cytotoxic leukocytes. However, only in recent years have studies shown that galectin-1 appears to perform a pro-inflammatory role in certain diseases. In this review, we describe the anti-inflammatory function of galectin-1 and its possible mechanisms and summarize the existing therapies and preclinical efficacy relating to these agents. In the meantime, we also discuss the potential causal factors by which galectin-1 promotes the progression of inflammation.

High serum levels of galectins 1 and 4 in osteoarthritis patients

BACKGROUND

Although immunostaining of galectins is associated with cartilage damage, the serum levels of these lectins in osteoarthritis (OA) are not fully understood.

OBJECTIVE

Therefore, we evaluate the concentrations of galectins-1, 3, 4, and 7 in patients with osteoarthritis and correlate them with clinical parameters.

METHODS

This cross-sectional study involved 60 osteoarthritis patients and 43 healthy volunteers, who had serum samples collected for galectins titration by Enzyme-Linked Immunosorbent Assay (ELISA).

RESULTS

Our finds showed that the median values of gal-1 and 4 serum levels in patients were statistically higher (13,990 and 969.1 pg/mL, respectively) than in healthy controls (1,798 and 519.5 pg/mL) with p < 0.001. Further, gal-1 expressed higher levels in patients who had joint edema at the time of collection with a median value of 14,970 pg/mL.

CONCLUSION

Surprisingly, galectin-4 appears to be involved in the osteoarthritis inflammation process as the well-known galectin-1.

The sweet side of wound healing: galectins as promising therapeutic targets in hemostasis, inflammation, proliferation, and maturation/remodeling

INTRODUCTION

Understanding the molecular and cellular processes involved in skin wound healing may pave the way for the development of innovative approaches to transforming the identified natural effectors into therapeutic tools. Based on the extensive involvement of the ga(lactoside-binding)lectin family in (patho)physiological processes, it has been well established that galectins are involved in a wide range of cell-cell and cell-matrix interactions.

AREAS COVERED

In the present paper, we provide an overview of the biological role of galectins in repair and regeneration, focusing on four main phases (hemostasis, inflammation, proliferation, and maturation/remodeling) of skin repair using basic wound models (open excision vs. sutured incision).

EXPERT OPINION

The reported data make a strong case for directing further efforts to treat excisional and incisional wounds differently. Functions of galectins essentially result from their modular presentation. In fact, Gal-1 seems to play a role in the early phases of healing (anti-inflammatory) and wound contraction, Gal-3 accelerates re-epithelization and increases tensile strength (scar inductor). Galectins have also become subject of redesigning by engineering to optimize the activity. Clinically relevant, these new tools derived from the carbohydrate recognition domain platform may also prove helpful for other purposes, such as potent antibacterial agglutinins and opsonins.

Targeting osteoarthritis-associated galectins and an induced effector class by a ditopic bifunctional reagent: Impact of its glycan part on binding measured in the tissue context

Pairing glycans with tissue lectins controls multiple effector pathways in (patho)physiology. A clinically relevant example is the prodegradative activity of galectins-1 and -3 (Gal-1 and -3) in the progression of osteoarthritis (OA) via matrix metalloproteinases (MMPs), especially MMP-13. The design of heterobifunctional inhibitors that can block galectin binding and MMPs both directly and by preventing their galectin-dependent induction selectively offers a perspective to dissect the roles of lectins and proteolytic enzymes. We describe the synthesis of such a reagent with a bivalent galectin ligand connected to an MMP inhibitor and of two tetravalent glycoclusters with a subtle change in headgroup presentation for further elucidation of influence on ligand binding. Testing was performed on clinical material with mixtures of galectins as occurring in vivo, using sections of fixed tissue. Two-colour fluorescence microscopy monitored binding to the cellular glycome after optimization of experimental parameters. In the presence of the inhibitor, galectin binding to OA specimens was significantly reduced. These results open the perspective to examine the inhibitory capacity of custom-made ditopic compounds on binding of lectins in mixtures using sections of clinical material with known impact of galectins and MMPs on disease progression.

Maackia amurensis seed lectin (MASL) ameliorates articular cartilage destruction and increases movement velocity of mice with TNFα induced rheumatoid arthritis

Up to 70 million people around the world suffer from rheumatoid arthritis. Current treatment options have varied efficacy and can cause unwanted side effects. New approaches are needed to treat this condition. Sialic acid modifications on chondrocyte receptors have been associated with arthritic inflammation and joint destruction. For example, the transmembrane mucin receptor protein podoplanin (PDPN) has been identified as a functionally relevant receptor that presents extracellular sialic acid motifs. PDPN signaling promotes inflammation and invasion associated with arthritis and, therefore, has emerged as a target that can be used to inhibit arthritic inflammation. Maackia amurensis seed lectin (MASL) can target PDPN on chondrocytes to decrease inflammatory signaling cascades and reduce cartilage destruction in a lipopolysaccharide induced osteoarthritis mouse model. Here, we investigated the effects of MASL on rheumatoid arthritis progression in a TNFα transgenic (TNF-Tg) mouse model. Results from this study indicate that MASL can be administered orally to ameliorate joint malformation and increase velocity of movement exhibited by these TNF-Tg mice. These data support the consideration of MASL as a potential treatment for rheumatoid arthritis.

A Dynamic Interplay of Circulating Extracellular Vesicles and Galectin-1 Reprograms Viral Latency during HIV-1 Infection

Combined Antiretroviral therapy (cART) suppresses HIV replication but fails to eradicate the virus, which persists in a small pool of long-lived latently infected cells. Immune activation and residual inflammation during cART are considered to contribute to viral persistence. Galectins, a family of β-galactoside-binding proteins, play central roles in host-pathogen interactions and inflammatory responses. Depending on their structure, glycan binding specificities and/or formation of distinct multivalent signaling complexes, different members of this family can complement, synergize, or oppose the function of others. Here, we identify a regulatory circuit, mediated by galectin-1 (Gal-1)–glycan interactions, that promotes reversal of HIV-1 latency in infected T cells. We found elevated levels of circulating Gal-1 in plasma from HIV-1-infected individuals, which correlated both with inflammatory markers and the transcriptional activity of the reservoir, as determined by unspliced-RNA (US-RNA) copy number. Proinflammatory extracellular vesicles (EVs) isolated from the plasma of HIV-infected individuals induced Gal-1 secretion by macrophages. Extracellularly, Gal-1 interacted with latently infected resting primary CD4⁺ T cells and J-LAT cells in a glycan-dependent manner and reversed HIV latency via activation of the nuclear factor κB (NF-κB). Furthermore, CD4⁺ T cells isolated from HIV-infected individuals showed increased HIV-1 transcriptional activity when exposed to Gal-1. Thus, by modulating reservoir dynamics, EV-driven Gal-1 secretion by macrophages links inflammation with HIV-1 persistence in cART-treated individuals.

TGFβ1-modified MSC-derived exosome attenuates osteoarthritis by inhibiting PDGF-BB secretion and H-type vessel activity in the subchondral bone

BACKGROUND

Greater bone resorption increases TGF-β1 release and nestin-positive BMSC recruitment to the subchondral bone marrow, leading to excessive subchondral osteophyte formation and severe wear to articular cartilage. Our previous research demonstrated that BMSCs-Exo^TGF-β1 attenuated cartilage damage in osteoarthritis (OA) rats through carrying highly expressed miR-135b.

METHODS

The bone marrow mesenchymal stem cells (BMSCs) were isolated from mouse bone marrow, and BMSC-derived exosomes (BMSCs-Exo) were isolated from BMSCs. OA mouse models were established by anterior cruciate ligament transection (ACLT) surgery on the left knee of mice. Then we explored the therapeutic effect of BMSCs-Exo^TGF-β1 on ACLT mice.

RESULTS

BMSCs-Exo^TGF-β1 attenuated cartilage damage in OA mice in vivo by ameliorating articular cartilage degeneration and suppressing calcification of the cartilage zone. BMSCs-Exo^TGF-β1 also inhibited osteoclastogenesis by suppressing the MAPK pathway in vitro. Micro-computed tomography indicated that BMSCs-Exo^TGF-β1 impeded uncoupled subchondral bone remodeling. BMSCs-Exo^TGF-β1 also reduced CD31^hiEmcn^hi vessel activity in the subchondral bone and attenuated OA pain behaviors.

CONCLUSIONS

In conclusion, BMSCs-Exo^TGF-β1 maintains the microarchitecture, inhibits abnormal angiogenesis in subchondral bone and exerts protective effect against OA-induced pain and bone resorption on ACLT mice.

DATA AVAILABILITY

The datasets are available from the corresponding author on reasonable request.

What is the Sugar Code?

A code is defined by the nature of the symbols, which are used to generate information-storing combinations (e. g. oligo- and polymers). Like nucleic acids and proteins, oligo- and polysaccharides are ubiquitous, and they are a biochemical platform for establishing molecular messages. Of note, the letters of the sugar code system (third alphabet of life) excel in coding capacity by making an unsurpassed versatility for isomer (code word) formation possible by variability in anomery and linkage position of the glycosidic bond, ring size and branching. The enzymatic machinery for glycan biosynthesis (writers) realizes this enormous potential for building a large vocabulary. It includes possibilities for dynamic editing/erasing as known from nucleic acids and proteins. Matching the glycome diversity, a large panel of sugar receptors (lectins) has developed based on more than a dozen folds. Lectins 'read' the glycan-encoded information. Hydrogen/coordination bonding and ionic pairing together with stacking and C-H/π-interactions as well as modes of spatial glycan presentation underlie the selectivity and specificity of glycan-lectin recognition. Modular design of lectins together with glycan display and the nature of the cognate glycoconjugate account for the large number of post-binding events. They give an entry to the glycan vocabulary its functional, often context-dependent meaning(s), hereby building the dictionary of the sugar code.

Role of Pyroptosis in Inflammatory Bowel Disease (IBD): From Gasdermins to DAMPs

Pyroptosis is a pro-inflammatory cell death executed by gasdermin family proteins that involve the formation of pores on cells, recognition of danger signals, and release of pro-inflammatory cytokines IL-1β and IL-18. Pyroptosis modulates mucosal innate immunity and enteropathogenic bacterial infection. Similarly, the gasdermin family has been reported to be involved in the defense of the intestinal epithelium against bacterial infection and in the regulation of intestinal inflammation. Pyroptosis initiates damage signals that activate multiple pathways to cause inflammation, which may be a potential cause of chronic intestinal inflammation. In this review, we discuss the impact of pyroptosis on inflammatory bowel disease (IBD), with a focus on the executive proteins of pyroptosis (GSDMB, GADMD, and GSDME) and IBD-related endogenous damage-associated molecular patterns (DAMPs) produced by pyroptosis.

Galectin-1 orchestrates an inflammatory tumor-stroma crosstalk in hepatoma by enhancing TNFR1 protein stability and signaling in carcinoma-associated fibroblasts

Most cases of hepatocellular carcinoma (HCC) arise with the fibrotic microenvironment where hepatic stellate cells (HSCs) and carcinoma-associated fibroblasts (CAFs) are critical components in HCC progression. Therefore, CAF normalization could be a feasible therapy for HCC. Galectin-1 (Gal-1), a β-galactoside-binding lectin, is critical for HSC activation and liver fibrosis. However, few studies has evaluated the pathological role of Gal-1 in HCC stroma and its role in hepatic CAF is unclear. Here we showed that Gal-1 mainly expressed in HCC stroma, but not cancer cells. High expression of Gal-1 is correlated with CAF markers and poor prognoses of HCC patients. In co-culture systems, targeting Gal-1 in CAFs or HSCs, using small hairpin (sh)RNAs or an therapeutic inhibitor (LLS30), downregulated plasminogen activator inhibitor-2 (PAI-2) production which suppressed cancer stem-like cell properties and invasion ability of HCC in a paracrine manner. The Gal-1-targeting effect was mediated by increased a disintegrin and metalloprotease 17 (ADAM17)-dependent TNF-receptor 1 (TNFR1) shedding/cleavage which inhibited the TNF-α → JNK → c-Jun/ATF2 signaling axis of pro-inflammatory gene transcription. Silencing Gal-1 in CAFs inhibited CAF-augmented HCC progression and reprogrammed the CAF-mediated inflammatory responses in a co-injection xenograft model. Taken together, the findings uncover a crucial role of Gal-1 in CAFs that orchestrates an inflammatory CSC niche supporting HCC progression and demonstrate that targeting Gal-1 could be a potential therapy for fibrosis-related HCC.

Galectin-8, cytokines, and the storm

Galectin-8 (Gal-8) belongs to a family of animal lectins that modulate cell adhesion, cell proliferation, apoptosis, and immune responses. Recent studies have shown that mammalian Gal-8 induces in an autocrine and paracrine manner, the expression and secretion of cytokines and chemokines such as RANKL, IL-6, IL-1β, SDF-1, and MCP-1. This involves Gal-8 binding to receptor complexes that include MRC2/uPAR/LRP1, integrins, and CD44. Receptors ligation triggers FAK, ERK, Akt, and the JNK signaling pathways, leading to induction of NF-κB that promotes cytokine expression. Indeed, immune-competent Gal-8 knockout (KO) mice express systemic lower levels of cytokines and chemokines while the opposite is true for Gal-8 transgenic animals. Cytokine and chemokine secretion, induced by Gal-8, promotes the migration of cancer cells toward cells expressing this lectin. Accordingly, Gal-8 KO mice experience reduced tumor size and smaller and fewer metastatic lesions when injected with cancer cells. These observations suggest the existence of a ‘vicious cycle’ whereby Gal-8 expression and secretion promotes the secretion of cytokines and chemokines that further promote Gal-8 expression. This ‘vicious cycle’ could enhance the development of a ‘cytokine storm’ which is a key contributor to the poor prognosis of COVID-19 patients.

Galectin network in osteoarthritis: galectin-4 programs a pathogenic signature of gene and effector expression in human chondrocytes in vitro

Galectin-4 (Gal-4) is a member of the galectin family, which have been identified as galactose-binding proteins. Gal-4 possesses two tandem repeat carbohydrate recognition domains and acts as a cross-linking bridge in sulfatide-dependent glycoprotein routing. We herein document its upregulation in osteoarthritis (OA) in correlation with the extent of cartilage degradation in vivo. Primary human OA chondrocytes in vitro respond to carbohydrate-inhibitable Gal-4 binding with the upregulation of pro-degradative/-inflammatory proteins such as interleukin-1β (IL-1β) and matrix metalloproteinase-13 (MMP-13), as documented by RT-qPCR-based mRNA profiling and transcriptome data processing. Activation of p65 by phosphorylation of Ser536 within the NF-κB pathway and the effect of three p65 inhibitors on Gal-4 activity support downstream involvement of such signaling. In 3D (pellet) cultures, Gal-4 presence causes morphological and biochemical signs of degradation. Taken together, our findings strongly support the concept of galectins acting as a network in OA pathogenesis and suggest that blocking their activity in disease progression may become clinically relevant in the future.

Therapeutic Benefit of Galectin-1: Beyond Membrane Repair, a Multifaceted Approach to LGMD2B

Two of the main pathologies characterizing dysferlinopathies are disrupted muscle membrane repair and chronic inflammation, which lead to symptoms of muscle weakness and wasting. Here, we used recombinant human Galectin-1 (rHsGal-1) as a therapeutic for LGMD2B mouse and human models. Various redox and multimerization states of Gal-1 show that rHsGal-1 is the most effective form in both increasing muscle repair and decreasing inflammation, due to its monomer-dimer equilibrium. Dose-response testing shows an effective 25-fold safety profile between 0.54 and 13.5 mg/kg rHsGal-1 in Bla/J mice. Mice treated weekly with rHsGal-1 showed downregulation of canonical NF-κB inflammation markers, decreased muscle fat deposition, upregulated anti-inflammatory cytokines, increased membrane repair, and increased functional movement compared to non-treated mice. Gal-1 treatment also resulted in a positive self-upregulation loop of increased endogenous Gal-1 expression independent of NF-κB activation. A similar reduction in disease pathologies in patient-derived human cells demonstrates the therapeutic potential of Gal-1 in LGMD2B patients.

The marriage of chemokines and galectins as functional heterodimers

Trafficking of leukocytes and their local activity profile are of pivotal importance for many (patho)physiological processes. Fittingly, microenvironments are complex by nature, with multiple mediators originating from diverse cell types and playing roles in an intimately regulated manner. To dissect aspects of this complexity, effectors are initially identified and structurally characterized, thus prompting familial classification and establishing foci of research activity. In this regard, chemokines present themselves as role models to illustrate the diversification and fine-tuning of inflammatory processes. This in turn discloses the interplay among chemokines, their cell receptors and cognate glycosaminoglycans, as well as their capacity to engage in new molecular interactions that form hetero-oligomers between themselves and other classes of effector molecules. The growing realization of versatility of adhesion/growth-regulatory galectins that bind to glycans and proteins and their presence at sites of inflammation led to testing the hypothesis that chemokines and galectins can interact with each other by protein-protein interactions. In this review, we present some background on chemokines and galectins, as well as experimental validation of this chemokine-galectin heterodimer concept exemplified with CXCL12 and galectin-3 as proof-of-principle, as well as sketch out some emerging perspectives in this arena.

Therapeutic potential of galectin-1 and galectin-3 in autoimmune diseases

Galectins are a highly conserved protein family that binds to β-galactosides. Different members of this family play a variety of biological functions in physiological and pathological processes such as angiogenesis, regulation of immune cell activity, and cell adhesion. Galectins are widely distributed and play a vital role both inside and outside cells. It can regulate homeostasis and immune function in vivo through mechanisms such as apoptosis. Recent studies indicate that galectins exhibit pleiotropic roles in inflammation. Furthermore, emerging studies have found that galectins are involved in the occurrence and development of autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), type 1 diabetes (T1D) and systemic sclerosis (SSc) by regulating cell adhesion, apoptosis, and other mechanisms. This review will briefly discuss the biological characteristics of the two most widely expressed and extensively explored members of the galectin family, galectin-1 and galectin-3, as well as their pathogenetic and therapeutic roles in autoimmune diseases. These information may provide a novel and promising therapeutic target for autoimmune diseases.

Knockdown of TRIM8 Attenuates IL-1β-induced Inflammatory Response in Osteoarthritis Chondrocytes Through the Inactivation of NF-κB Pathway

Osteoarthritis (OA) is a degenerative joint disease associated with inflammatory response. Tripartite motif 8 (TRIM8) is a member of TRIM family that has been found to regulate inflammation. The present study was aimed to evaluate the role of TRIM8 in OA chondrocytes. Our results showed that TRIM8 expression was significantly increased in interleukin 1 beta (IL-1β)-stimulated OA chondrocytes. To knock down the TRIM8 expression in chondrocytes, the chondrocytes were transfected with si-TRIM8. Knockdown of TRIM8 attenuated IL-1β-induced production of inflammatory mediators including nitric oxide and prostaglandin E₂. The increased expression levels of inducible nitric oxide synthase and cyclooxygenase-2 in IL-1β-induced chondrocytes were suppressed by TRIM8 knockdown. The IL-1β-induced production of proinflammatory cytokines including TNF-α and IL-6 was significantly decreased after transfection with si-TRIM8. Besides, knockdown of TRIM8 mitigated the IL-1β-induced decrease in aggrecan and collagen-II proteins expression and increase in matrix-degrading enzymes in chondrocytes. Furthermore, TRIM8 knockdown prevented IL-1β-induced nuclear factor kappa B (NF-κB) activation in chondrocytes. Taken together, these findings indicated that knockdown of TRIM8 attenuates IL-1β-induced inflammatory response in OA chondrocytes through the inactivation of NF-κB pathway. Thus, targeting TRIM8 might provide therapeutic treatment for OA.

Emerging role of galectin family in inflammatory autoimmune diseases

Galectin family is a group of glycan-binding proteins. Members in this family are expressed in different tissues, immune or non-immune cells. These molecules are important regulators in innate and adaptive immune response, performing significantly in a broad range of cellular and pathophysiological functions, such as cell proliferation, adhesion, migration, and invasion. Findings have shown that expression of galectins is abnormal in many inflammatory autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, osteoarthritis, sjögren's syndrome, systemic sclerosis. Galectins also function as intracellular and extracellular disease regulators mainly through the binding of their carbohydrate recognition domain to glycoconjugates. Here, we review the state-of-the-art of the role that different galectin family members play in immune cells, contributing to the complex inflammatory diseases. Hopefully collection of the information will provide a preliminary theoretical basis for the exploration of new targets for treatment of the disorders.

N-Glycan profiling of chondrocytes and fibroblast-like synoviocytes: Towards functional glycomics in osteoarthritis

PURPOSE

N-Glycan profiling provides an indicator of the cellular potential for functional pairing with tissue lectins. Following the discovery of galectin expression by chondrocytes as a factor in osteoarthritis pathobiology, mapping of N-glycans upon their phenotypic dedifferentiation in culture and in fibroblast-like synoviocytes is a step to better understand glycobiological contributions to disease progression.

EXPERIMENTAL DESIGN

The profiles of cellular N-glycans of human osteoarthritic chondrocytes and fibroblast-like synoviocytes were characterized by mass spectrometry. RT-qPCR experiments determined mRNA levels of 16 glycosyltransferases. Responsiveness of cells to galectins was quantified by measuring the mRNA level for interleukin-1β.

RESULTS

The shift of chondrocytes to a fibroblastic phenotype (dedifferentiation) is associated with changes in N-glycosylation. The N-glycan profile of chondrocytes at passage 4 reflects characteristics of synoviocytes. Galectins-1 and -3 enhance expression of interleukin-1β mRNA in both cell types, most pronounced in primary culture. Presence of interleukin-1β leads to changes in sialylation in synoviocytes that favor galectin binding.

CONCLUSIONS AND CLINICAL RELEVANCE

N-Glycosylation reflects phenotypic changes of osteoarthritic cells in vitro. Like chondrocytes, fibroblast-like synoviocytes express N-glycans that are suited to bind galectins, and these proteins serve as inducers of pro-inflammatory markers in these cells. Synoviocytes can thus contribute to disease progression in osteoarthritis in situ.

Age-related trabecular bone loss is associated with a decline in serum Galectin-1 level

BACKGROUND

Senile osteoporosis with age-related bone loss is diagnosed depending on radiographic changes of bone and bone mineral density (BMD) measurement. However, radiographic alterations are usually signs of medium-late stage osteoporosis. Therefore, biomarkers have been proposed as indicators of bone loss. In the current study, Galectin-1 (Gal-1) showed age-related decline in mice serum. The role of Gal-1 in osteoporosis has not been investigated so far. Hence, the current study illustrated the relationship of serum Gal-1 level with bone loss.

METHODS

We employed 6- and 18-month-old mice to establish an animal model of age-related trabecular bone loss, whose bone density and microstructure were investigated by micro-CT. ELISA was used to measure the levels of Gal-1 in serum. The correlation analysis was performed to illustrate the relationship between serum Gal-1 levels and trabecular bone loss. In addition, immunohistochemistry was used to investigate the abundance of Gal-1 in bone marrow of mice. ELISA and western blot were performed to measure the secretion ability and protein expression of Gal-1 in bone marrow stromal cells (BMSC), hematopoietic stem cells (HSC) and myeloid progenitor (MP) respectively. Flow cytometry was used to measure BMSC number in bone marrow. Finally, male volunteers with age-related BMD decrease were recruited and the relationship between serum Gal-1 and BMD was analyzed.

RESULTS

Gal-1 showed age-related decline in mice serum. Serum Gal-1 was positively associated with BV/TV of femur, tibia and L1 vertebrae in mice. BMSC secreted more Gal-1 compared with HSC and MP. BMSC number in bone marrow was significantly lower in aged mice compared with young mice. Significant attenuation of Gal-1 protein expression was observed in BMSC and HSC from aged mice compared with young mice. Further, we found a decline in serum Gal-1 levels in men with age-related BMD decrease. There was positive correlation between BMD and serum Gal-1 levels in these men.

CONCLUSIONS

Age-related trabecular bone loss is associated with a decline in serum Gal-1 level in mice and men. Our study suggested Gal-1 had great potential to be a biomarker for discovering BMSC senescence, diagnosing early osteoporosis and monitoring trabecular bone loss.

Combining bulk and single-cell RNA-sequencing data to reveal gene expression pattern of chondrocytes in the osteoarthritic knee

Osteoarthritis (OA) occurs mostly in the knees, hips, finger interphalangeal joints, and spinal facet joints, and is characterized by cartilage degeneration. The existing bulk RNA sequencing (bulk RNA-seq) and single-cell sequencing (scRNA-seq) data for chondrocytes in the osteoarthritic knee joint provide the expression profiles of entire cell populations and individual cells, respectively. Here, we aimed to analyze these two types of sequencing data in order to obtain a more comprehensive understanding of OA. We compared the analysis results of bulk RNA-seq and scRNA-seq from the dataset GSE114007 and the dataset GSE104782, respectively, and identified the differentially expressed genes (DEGs). Then, we tried to find the key The transcription factor is a more fomal term (TFs) and long non-coding RNA (lncRNA) regulation. We highlighted 271 genes that were simultaneously suggested by these two types of data and provided their possible expression pattern in OA. Among the 271 genes, we identified 14 TFs, and TWIST2, MYBL2, RELA, JUN, KLF4, and PTTG1 could be the key TFs for the 271 genes. We also found that 8 lncRNAs among the 271 genes and the lncRNA regulation between CYTOR and NRP1 could contribute to the pain and vascularization of cartilage in the osteoarthritic knee. In short, our research combined the analysis results of bulk RNA-seq and scRNA-seq data for OA chondrocytes, which will contribute to further elucidation of the molecular mechanisms of OA pathogenesis.

The Dysregulated Galectin Network Activates NF-κB to Induce Disease Markers and Matrix Degeneration in 3D Pellet Cultures of Osteoarthritic Chondrocytes

This work aimed to study the dysregulated network of galectins in OA chondrocyte pellets, and to assess whether their recently discovered activity as molecular switches of functional biomarkers results in degradation of extracellular matrix in vitro. Scaffold-free 3D pellet cultures were established of human OA chondrocytes. Expression and secretion of galectin(Gal)-1, -3, and -8 were monitored relative to 2D cultures or clinical tissue sections by RT-qPCR, immunohistochemistry and ELISAs. Exposure of 2D and 3D cultures to an in vivo-like galectin mixture (Gal-1 and Gal-8: 5 µg/ml, Gal-3: 1 µg/ml) was followed by the assessment of pellet size, immunohistochemical matrix staining, and/or quantification of MMP-1, -3, and -13. Application of inhibitors of NF-κB activation probed into the potential of intervening with galectin-induced matrix degradation. Galectin profiling revealed maintained dysregulation of Gal-1, -3, and -8 in pellet cultures, resembling the OA situation in situ. The presence of the galectin mixture promoted marked reduction of pellet size and loss of collagen type II-rich extracellular matrix, accompanied by the upregulation of MMP-1, -3, and -13. Inhibition of p65-phosphorylation by caffeic acid phenethyl ester effectively alleviated the detrimental effects of galectins, resulting in downregulated MMP secretion, reduced matrix breakdown and augmented pellet size. This study suggests that the dysregulated galectin network in OA cartilage leads to extracellular matrix breakdown, and provides encouraging evidence of the feasible inhibition of galectin-triggered activities. OA chondrocyte pellets have the potential to serve as in vitro disease model for further studies on galectins in OA onset and progression.

Tissue-specific control of galectin-1-driven circuits during inflammatory responses

The relevance of glycan-binding protein in immune tolerance and inflammation has been well established, mainly by studies of C-type lectins, siglecs and galectins both in experimental models and patient samples. Galectins, a family of evolutionarily conserved lectins, are characterized by sequence homology in the carbohydrate-recognition domain (CRD), atypical secretion via an ER-Golgi-independent pathway and the ability to recognize β-galactoside-containing saccharides. Galectin-1 (Gal-1), a prototype member of this family displays mainly anti-inflammatory and immunosuppressive activities, although, similar to many cytokines and growth factors, it may also trigger paradoxical pro-inflammatory effects under certain circumstances. These dual effects could be associated to tissue-, time- or context-dependent regulation of galectin expression and function, including particular pathophysiologic settings and/or environmental conditions influencing the structure of this lectin, as well as the availability of glycosylated ligands in immune cells during the course of inflammatory responses. Here, we discuss the tissue-specific role of Gal-1 as a master regulator of inflammatory responses across different pathophysiologic settings, highlighting its potential role as a therapeutic target. Further studies designed at analyzing the intrinsic and extrinsic pathways that control Gal-1 expression and function in different tissue microenvironments may contribute to design tailored therapeutic strategies aimed at positively or negatively modulate this glycan-binding protein in pathologic inflammatory conditions.

Intracellular immune sensing promotes inflammation via gasdermin D-driven release of a lectin alarmin

Inflammatory caspase sensing of cytosolic lipopolysaccharide (LPS) triggers pyroptosis and the concurrent release of damage-associated molecular patterns (DAMPs). Collectively, DAMPs are key determinants that shape the aftermath of inflammatory cell death. However, the identity and function of the individual DAMPs released are poorly defined. Our proteomics study revealed that cytosolic LPS sensing triggered the release of galectin-1, a β-galactoside-binding lectin. Galectin-1 release is a common feature of inflammatory cell death, including necroptosis. In vivo studies using galectin-1-deficient mice, recombinant galectin-1 and galectin-1-neutralizing antibody showed that galectin-1 promotes inflammation and plays a detrimental role in LPS-induced lethality. Mechanistically, galectin-1 inhibition of CD45 (Ptprc) underlies its unfavorable role in endotoxin shock. Finally, we found increased galectin-1 in sera from human patients with sepsis. Overall, we uncovered galectin-1 as a bona fide DAMP released as a consequence of cytosolic LPS sensing, identifying a new outcome of inflammatory cell death.

Human galectin‑3: Molecular switch of gene expression in dermal fibroblasts in vitro and of skin collagen organization in open wounds and tensile strength in incisions in vivo

Understanding the molecular and cellular processes in skin wound healing can pave the way for devising innovative concepts by turning the identified natural effectors into therapeutic tools. Based on the concept of broad-scale engagement of members of the family of galactoside-binding lectins (galectins) in pathophysiological processes, such as cancer or tissue repair/regeneration, the present study investigated the potential of galectins-1 (Gal-1) and −3 (Gal-3) in wound healing. Human dermal fibroblasts, which are key cells involved in skin wound healing, responded to galectin exposure (Gal-1 at 300 or Gal-3 at 600 ng/ml) with selective changes in gene expression among a panel of 84 wound-healing-related genes, as well as remodeling of the extracellular matrix. In the case of Gal-3, positive expression of Ki67 and cell number increased when using a decellularized matrix produced by Gal-3-treated fibroblasts as substrate for culture of interfollicular keratinocytes. In vivo wounds were topically treated with 20 μg/ml Gal-1 or −3, and collagen score was found to be elevated in excisional wound repair in rats treated with Gal-3. The tensile strength measured in incisions was significantly increased from 79.5±17.5 g/mm² in controls to 103.1±21.4 g/mm² after 21 days of healing. These data warrant further testing mixtures of galectins and other types of compounds, for example a combination of galectins and TGF-β1.

Anti-Inflammatory Performance of Lactose-Modified Chitosan and Hyaluronic Acid Mixtures in an In Vitro Macrophage-Mediated Inflammation Osteoarthritis Model

The development and progression of osteoarthritis (OA) is associated with macrophage-mediated inflammation that generates a broad spectrum of cytokines and reactive oxygen species (ROS). This study investigates the effects of mid-MW hyaluronic acid (HA) in combination with a lactose-modified chitosan (CTL), on pro-inflammatory molecules and metalloproteinases (MMPs) expression, using an in vitro model of macrophage-mediated inflammation. Methods. To assess chondrocyte response to HA and CTL in the presence of macrophage derived inflammatory mediators, cells were exposed to the conditioned medium (CM) of U937 activated monocytes and changes in cell viability, pro-inflammatory mediators and MMPs expression or ROS generation were analysed. Results. CTL induced changes in chondrocyte viability that are reduced by the presence of HA. The CM of activated U937 monocytes (macrophages) significantly increased gene expression of pro-inflammatory molecules and MMPs and intracellular ROS generation in human chondrocyte cultures. HA, CTL and their combinations counteracted the oxidative damage and restored gene transcription for IL-1β, TNF-α, Gal-1, MMP-3 and MMP-13 to near baseline values. Conclusions. This study suggests that HA-CTL mixture attenuated macrophage-induced inflammation, inhibited MMPs expression and exhibited anti-oxidative effects. This evidence provides an initial step toward the development of an early stage OA therapeutic treatment

New Therapeutic Strategies for Osteoarthritis by Targeting Sialic Acid Receptors

Osteoarthritis (OA) is the most common degenerative joint disease characterized by articular cartilage degradation and joint degeneration. The articular cartilage is mainly formed by chondrocytes and a collagen-proteoglycan extracellular matrix that contains high levels of glycosylated proteins. It was reported that the shift from glycoproteins containing α-2,6-linked sialic acids to those that contain α-2,3 was associated with the onset of common types of arthritis. However, the pathophysiology of α-2,3-sialylation in cartilage has not been yet elucidated. We show that cartilage from osteoarthritic patients expresses high levels of the α-2,3-sialylated transmembrane mucin receptor, known as podoplanin (PDPN). Additionally, the Maackia amurensis seed lectin (MASL), that can be utilized to target PDPN, attenuates the inflammatory response mediated by NF-kB activation in primary chondrocytes and protects human cartilage breakdown ex vivo and in an animal model of arthritis. These findings reveal that specific lectins targeting α-2,3-sialylated receptors on chondrocytes might effectively inhibit cartilage breakdown. We also present a computational 3D molecular model for this interaction. These findings provide mechanistic information on how a specific lectin could be used as a novel therapy to treat degenerative joint diseases such as osteoarthritis.

Chemokines and galectins form heterodimers to modulate inflammation

Chemokines and galectins are simultaneously upregulated and mediate leukocyte recruitment during inflammation. Until now, these effector molecules have been considered to function independently. Here, we tested the hypothesis that they form molecular hybrids. By systematically screening chemokines for their ability to bind galectin‐1 and galectin‐3, we identified several interacting pairs, such as CXCL12 and galectin‐3. Based on NMR and MD studies of the CXCL12/galectin‐3 heterodimer, we identified contact sites between CXCL12 β‐strand 1 and Gal‐3 F‐face residues. Mutagenesis of galectin‐3 residues involved in heterodimer formation resulted in reduced binding to CXCL12, enabling testing of functional activity comparatively. Galectin‐3, but not its mutants, inhibited CXCL12‐induced chemotaxis of leukocytes and their recruitment into the mouse peritoneum. Moreover, galectin‐3 attenuated CXCL12‐stimulated signaling via its receptor CXCR4 in a ternary complex with the chemokine and receptor, consistent with our structural model. This first report of heterodimerization between chemokines and galectins reveals a new type of interaction between inflammatory mediators that can underlie a novel immunoregulatory mechanism in inflammation. Thus, further exploration of the chemokine/galectin interactome is warranted.

How galectins have become multifunctional proteins

Having identified glycans of cellular glycoconjugates as versatile molecular messages, their recognition by sugar receptors (lectins) is a fundamental mechanism within the flow of biological information. This type of molecular interplay is increasingly revealed to be involved in a wide range of (patho)physiological processes. To do so, it is a vital prerequisite that a lectin (and its expression) can develop more than a single skill, that is the general ability to bind glycans. By studying the example of vertebrate galectins as a model, a total of five relevant characteristics is disclosed: i) access to intra- and extracellular sites, ii) fine-tuned gene regulation (with evidence for co-regulation of counterreceptors) including the existence of variants due to alternative splicing or single nucleotide polymorphisms, iii) specificity to distinct glycans from the glycome with different molecular meaning, iv) binding capacity also to peptide motifs at different sites on the protein and v) diversity of modular architecture. They combine to endow these lectins with the capacity to serve as multi-purpose tools. Underscoring the arising broad-scale significance of tissue lectins, their numbers in terms of known families and group members have steadily grown by respective research that therefore unveiled a well-stocked toolbox. The generation of a network of (ga)lectins by evolutionary diversification affords the opportunity for additive/synergistic or antagonistic interplay in situ, an emerging aspect of (ga)lectin functionality. It warrants close scrutiny. The realization of the enormous potential of combinatorial permutations using the five listed features gives further efforts to understand the rules of functional glycomics/lectinomics a clear direction.

Shikonin induces colorectal carcinoma cells apoptosis and autophagy by targeting galectin-1/JNK signaling axis

Colorectal carcinoma (CRC) is the third most common malignant tumor pathology worldwide. Despite progress in surgical procedures and therapy options, CRC is still a considerable cause of cancer-related mortality. In this study, we tested the antitumor effects of shikonin in CRC and tried to identify its potential mechanism. The potential target, molecular mechanism as well as in vitro and in vivo antitumor effects of shikonin in CRC cells were determined by an integrative protocol including quantitative proteomics, RT-PCR, western blotting, RNA interference and overexpression, apoptosis and autophagy assays, etc. Galectin-1 was a potential target of shikonin from the iTRAQ-based proteomic analysis in shikonin-treated SW620 cell. The overexpression and RNA silencing of galectin-1 in two CRC cells suggested that the shikonin sensitivity was correlation to galectin-1 levels. The ROS accumulation induced by shikonin was important to the formation of galectin-1 dimers. Dimer galectin-1 was found to be associated with the activation of JNK and downstream apoptosis or autophagy. Moreover, through functional in vitro studies, we showed that differences in galectin-1 level affected tumor cell proliferation, migration, and invasion. In summary, shikonin induced CRC cells apoptosis and autophagy by targeting galectin-1 and JNK signaling pathway both in vitro and in vivo, which suggested a potential novel therapy target for CRC.

How presence of a signal peptide affects human galectins-1 and -4: Clues to explain common absence of a leader sequence among adhesion/growth-regulatory galectins

BACKGROUND

Galectins are multifunctional effectors, which all share absence of a signal sequence. It is not clear why galectins belong to the small set of proteins, which avoid the classical export route.

METHODS

Products of recombinant galectin expression in P. pastoris were analyzed by haemagglutination, gel filtration and electrophoresis and lectin blotting as well as mass spectrometry on the level of tryptic peptides and purified glycopeptides(s). Density gradient centrifugation and confocal laser scanning microscopy facilitated localization in transfected human and rat cells, proliferation assays determined activity as growth mediator.

RESULTS

Directing galectin-1 to the classical secretory pathway in yeast produces N-glycosylated protein that is active. It cofractionates and -localizes with calnexin in human cells, only Gal-4 is secreted. Presence of N-glycan(s) reduces affinity of cell binding and growth regulation by Gal-1.

CONCLUSIONS

Folding and activity of a galectin are maintained in signal-peptide-directed routing, N-glycosylation occurs. This pathway would deplete cytoplasm and nucleus of galectin, presence of N-glycans appears to interfere with lattice formation.

GENERAL SIGNIFICANCE

Availability of glycosylated galectins facilitates functional assays to contribute to explain why galectins invariably avoid classical routing for export.

Galectins-1 and -3 in Human Intervertebral Disc Degeneration: Non-Uniform Distribution Profiles and Activation of Disease Markers Involving NF-κB by Galectin-1

Degeneration of the human intervertebral disc (IVD) is assumed to underlie severe clinical symptoms, in particular chronic back pain. Since adhesion/growth-regulatory galectins are linked to arthritis/osteoarthritis pathogenesis by activating a pro-degradative/-inflammatory gene expression signature, we hypothesized a similar functional involvement of galectins in IVD degeneration. Immunohistochemical evidence for the presence of galectins-1 and -3 in IVD is provided comparatively for specimens of spondylochondrosis, spondylolisthesis, and spinal deformity. Immunopositivity was detected in sections of fixed IVD specimens in each cellular compartment with age-, disease-, and galectin-type-related differences. Of note, presence of both galectins correlated with IVD degeneration, whereas correlation with age was seen only for galectin-3. In addition, staining profiles for these two galectins showed different distribution patterns in serial sections, an indication for non-redundant functionalities. In vitro, both galectins bound to IVD cells in a glycan-dependent manner. However, exclusively galectin-1 binding triggered a significant induction of functional disease markers (i.e., IL6, CXCL8, and MMP1/3/13) with involvement of the nuclear factor-kB pathway. This study thus gives direction to further network analyses and functional studies on galectins in IVD degeneration. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2204-2216, 2019.

Inhibition of microRNA-495 suppresses chondrocyte apoptosis through activation of the NF-κB signaling pathway by regulating CCL4 in osteoarthritis

As a common form of arthritis, osteoarthritis (OA) represents a degenerative disease, characterized by articular cartilage damage and synovium inflammation. Recently, the role of various microRNAs (miRs) and their specific expression in OA has been highlighted. Therefore, the aim of the current study was to elucidate the role by which miR-495 and chemokine ligand 4 (CCL4) influence the development and progression of OA. OA mice models were established, after which the CCL4 and collagen levels as well as cell apoptosis were determined in cartilage tissue of OA mice. The chondrocytes of the OA mice models were subsequently treated with a series of miR-495 mimic, inhibitor, and siRNA against CCL4. Afterwards, miR-495 expressions as well as the levels of CCL4, p50, p65, and IkBa and the extent of IkBa phosphorylation in addition to the luciferase activity of NF-kB were measured accordingly. Finally, cell apoptosis and cell cycle distribution were detected. miR-495 was highly expressed while NF-κB, CCL4, and collagen II were poorly expressed. Cell apoptosis was elevated in the cartilage tissue of the OA mice. CCL4 was a potential target gene of miR-495. Downregulation of miR-495 led to accelerated chondrocyte proliferation accompanied by diminished cell apoptosis among the OA mice. Taken together, the results of the current study demonstrated that inhibition of miR-495 suppressed chondrocyte apoptosis and promoted its proliferation through activation of the NF-κB signaling pathway by up-regulation of CCL4 in OA.

Effects of intra-articular hyaluronic acid associated to Chitlac (arty-duo®) in a rat knee osteoarthritis model

Among conventional osteoarthritis (OA) treatments, intra-articular (i.a) viscosupplementation with hyaluronic acid (HA) is used to restore joint viscoelasticity. However, the rapid clearance and elimination of HA may limit its application. The aim of this study was to verify the improved efficacy of HA within the joint, using a lactose-modified chitosan (chitlac) as a potentially chondroprotective additive. Four weeks after induction of experimental OA by destabilization of the medial meniscus (DMM), 12-week-old Sprague Dawley male rats (n = 30), received once a week, for three weeks, i.a injections of: (i) HA associated to chitlac (ARTY-DUO®), (ii) HA; and (iii) sodium chloride (NaCl). Five animals for each group were euthanized 4 weeks after the first i.a injection, while the remaining five were euthanized 8 weeks after the first i.a injection. The restoration of physiological joint microenvironment was tested by histology, histomorphometry, immunohistochemistry, and microtomography (micro-CT). At 4 and even more at 8 weeks, histological analysis showed a significant decrease in OARSI and Mankin scores, with weaker matrix metalloproteinase (MMP)-3, MMP-13, and Galectin-3 in ARTY-DUO® group versus NaCl and HA groups. A reduction in Galectin-1 and a stronger Collagen II staining was seen in both ARTY-DUO® and HA versus NaCl. A reduction in Kreen-modified score, for synovium inflammation, was observed in the ARTY-DUO® group. Micro-CT measurements did not shown significant differences between the groups. The present results show that i.a ARTY-DUO® injections produce a significant improvement in knee articular cartilage degeneration and synovium inflammation in a rat model of DMM-induced OA. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Cortistatin binds to TNF-α receptors and protects against osteoarthritis

Background

Osteoarthritis (OA) is a common degenerative disease, and tumor necrosis factor (TNF-α) is known to play a critical role in OA. Cortistatin (CST) is a neuropeptide discovered over 20  years ago, which plays a vital role in inflammatory reactions. However, it is unknown whether CST is involved in cartilage degeneration and OA development.

Methods

The interaction between CST and TNF-α receptors was investigated through Coimmunoprecipitation and Biotin-based solid-phase binding assay. Western blot, Real-time PCR, ELISA, immunofluorescence staining, nitrite production assay and DMMB assay of GAG were performed for the primary chondrocyte experiments. Surgically induced and spontaneous OA models were established and western blot, flow cytometry, Real-time PCR, ELISA, immunohistochemistry and fluorescence in vivo imaging were performed for in vivo experiments.

Findings

CST competitively bound to TNFR1 as well as TNFR2. CST suppressed proinflammatory function of TNF-α. Both spontaneous and surgically induced OA models indicated that deficiency of CST led to an accelerated OA-like phenotype, while exogenous CST attenuated OA development in vivo. Additionally, TNFR1- and TNFR2-knockout mice were used for analysis and indicated that TNFRs might be involved in the protective role of CST in OA. CST inhibited activation of the NF-κB signaling pathway in OA.

Interpretation

This study provides new insight into the pathogenesis and therapeutic strategy of cartilage degenerative diseases, including OA.

Fund

The National Natural Science Foundation of China, the Natural Science Foundation of Shandong Province, Key Research and Development Projects of Shandong Province and the Cross-disciplinary Fund of Shandong University.

Association of IL-6, IL-8, MMP-13 gene polymorphisms with knee osteoarthritis susceptibility in the Chinese Han population

Objective: To identify the association between the interleukin (IL) 6 (IL-6) rs1800795 (-174 G>C), IL-8 rs4073 (-251T>A), and matrix metalloproteinase-13 (MMP-13) rs2252070 (-77G>A) gene polymorphisms and knee osteoarthritis (KOA) susceptibility in the Chinese Han population. Methods: Genomic DNA was extracted from a total of 400 KOA patients and 400 healthy subjects. Sanger sequencing was performed to determine the genotypes of the IL-6 rs1800795 (-174 G/C), IL-8 rs4073 (-251A/T), and MMP-13 rs2252070 (-77A/G) loci. The mRNA expression levels of IL-6, IL-8, and MMP-13 in osteoblasts and the protein expression levels of IL-6, IL-8, and MMP-13 in the synovial fluids of KOA patients were analyzed. Results: The recessive model of IL-6 rs1800795 locus was found to be associated with KOA risk (adjusted odds ratio (OR) = 1.657, 95% confidence interval (CI) = 1.396-1.866, P<0.001). The IL-8 rs4073 locus dominant and recessive model showed no significant association with KOA risk (P>0.05). The dominant and recessive models of the MMP-13 rs2252070 locus showed higher risk for developing KOA (dominant model: adjusted OR = 1.271, 95%CI = 1.095-1.480, P=0.001; recessive model: adjusted OR = 1.361 95%CI = 1.151-1.569, P<0.001). The G>C mutation in IL-6 rs1800795 and the G>A mutation in MMP-13 rs2252070 were associated with significantly higher KOA disease severity. The G>C mutation in the IL-6 rs1800795 locus was associated with up-regulation of IL-6 expression. The G>A mutation in the MMP-13 rs2252070 locus was associated with up-regulation of MMP-13 expression. Conclusion: The IL-8 rs4073 (-251T>A) mutation was not associated with KOA susceptibility. The IL-6 rs1800795 (-174 G>C) and MMP-13 rs2252070 (-77G>A) mutations were associated with KOA susceptibility, increased disease severity, and up-regulation of IL-6 and MMP-13 expression levels.

Clinical Relevance of Galectin-1 and Galectin-3 in Rheumatoid Arthritis Patients: Differential Regulation and Correlation With Disease Activity

Galectins, a family of animal lectins, play central roles in immune system regulation, shaping both innate and adaptive responses in physiological and pathological processes. These include rheumatoid arthritis (RA), a chronic multifactorial autoimmune disease characterized by inflammatory responses that affects both articular and extra-articular tissues. Galectins have been reported to play central roles in RA and its experimental animal models. In this perspective article we present new data highlighting the regulated expression of galectin-1 (Gal-1) and galectin-3 (Gal-3) in sera from RA patients under disease-modifying anti-rheumatic drugs (DMARDs) and/or corticoid treatment in the context of a more comprehensive discussion that summarizes the roles of galectins in joint inflammation. We found that Gal-1 levels markedly increase in sera from RA patients and positively correlate with erythrocyte sedimentation rate (ERS) and disease activity score 28 (DAS-28) parameters. On the other hand, Gal-3 is downregulated in RA patients, but positively correlates with health assessment questionnaire parameter (HAQ). Finally, by generating receiver-operator characteristic (ROC) curves, we found that Gal-1 and Gal-3 serum levels constitute good parameters to discriminate patients with RA from healthy individuals. Our findings uncover a differential regulation of Gal-1 and Gal-3 which might contribute to the anti-inflammatory effects elicited by DMARDs and corticoid treatment in RA patients.

Galectins-1 and-3 Increase in Equine Post-traumatic Osteoarthritis

Galectins are potent regulators of cell adhesion, growth and apoptosis in diverse cell types, including chondrocytes and synovial fibroblasts. Elevations in synovial fluid galectin-3 have been observed in rheumatoid arthritis, juvenile idiopathic arthritis and experimental inflammatory arthritis in animal models, whereas galectin-1 is thought to be protective. Less is known about galectins-1 and-3 in osteoarthritis (OA). Therefore, the purpose of this study was: (1) to determine whether galectin-1 and-3 synovial fluid concentrations and synovial membrane and cartilage histochemical staining were altered following osteochondral injury in an experimental equine osteoarthritis (OA) model and (2) to measure galectin-1 and-3 mRNA expression and synovial fluid concentrations in naturally occurring equine carpal OA. Synovial fluid galectin-1 and-3 concentrations were quantified using custom ELISAs in two research horse cohorts undergoing experimental OA induction (n = 5 and 4) and in a cohort of horses with naturally occurring carpal OA (n = 57). Galectin mRNA expression in synovial membrane and cartilage tissue obtained from carpal joints of horses with naturally occurring OA was measured using RT-qPCR, and galectin immunostaining was assessed in synovial membrane and osteochondral tissues in the experimental model (n = 5). Synovial fluid galectin-1 and-3 concentrations increased following experimental carpal osteochondral fragmentation. Cartilage galectin-1 mRNA expression increased with OA severity in naturally occurring disease. The superficial zone of healthy articular cartilage stained intensely for galectin-3 in sham-operated joints, whereas galectin-1 staining was nearly absent. Chondrocyte galectin-1 and-3 immunoreactivity increased following cartilage injury, particularly in galectin-1 positive chondrones. Galectins-1 and-3 are present in healthy equine synovial fluid and increase following post-traumatic OA. Healthy superficial zone chondrocytes express galectin-3, whereas galectin-1 chondrocyte staining is limited predominantly to chondrones and injured cartilage. Further work is needed to clarify the functions of galectins-1 and-3 in healthy and OA joints.

Galectin-8 induces functional disease markers in human osteoarthritis and cooperates with galectins-1 and -3

The reading of glycan-encoded signals by tissue lectins is considered a major route of the flow of biological information in many (patho)physiological processes. The arising challenge for current research is to proceed from work on a distinct protein to family-wide testing of lectin function. Having previously identified homodimeric galectin-1 and chimera-type galectin-3 as molecular switches in osteoarthritis progression, we here provide proof-of-principle evidence for an intra-network cooperation of galectins with three types of modular architecture. We show that the presence of tandem-repeat-type galectin-8 significantly correlated with cartilage degeneration and that it is secreted by osteoarthritic chondrocytes. Glycan-inhibitable surface binding of galectin-8 to these cells increased gene transcription and the secretion of functional disease markers. The natural variant galectin-8 (F19Y) was less active than the prevalent form. Genome-wide array analysis revealed induction of a pro-degradative/inflammatory gene signature, largely under control of NF-κB signaling. This signature overlapped with respective gene-expression patterns elicited by galectins-1 and -3, but also presented supplementary features. Functional assays with mixtures of galectins that mimic the pathophysiological status unveiled cooperation between the three galectins. Our findings shape the novel concept to consider individual galectins as part of a so far not realized teamwork in osteoarthritis pathogenesis, with relevance beyond this disease.

Brazilin blocks catabolic processes in human osteoarthritic chondrocytes via inhibition of NFKB1/p50

This study aimed to evaluate the chondroprotective and anti-inflammatory activity of brazilin in human osteoarthritic (OA) cartilage and chondrocytes with particular focus on the nuclear factor-kappa B (NF-κB) pathway. Therefore, brazilin was isolated from Caesalpinia sappan and identified using high performance liquid chromatography (HPLC). The effect of brazilin was assessed in cartilage explants treated with 10 ng/ml interleukin (IL)-1β and 10 ng/ml tumor necrosis factor (TNF)-α using histological and biochemical glycosaminoglycan (GAG) analyses and in primary chondrocytes treated with 10 ng/ml IL-1β using RT-qPCR, ELISA, and Western blot. The involvement of NF-κB signaling was examined using a human NF-κB signaling array and in silico pathway analysis. Brazilin was found to reduce the GAG loss from cartilage explants stimulated with IL-1β and TNF-α. NF-κB pathway analysis in chondrocytes revealed NFKB1/p50 as a central player regulating the anti-inflammatory activities of brazilin. Brazilin suppressed the IL-1β-mediated up-regulation of OA markers and the induction of NFKB1/p50 in chondrocytes. In conclusion, brazilin effectively attenuates catabolic processes in human OA cartilage and chondrocytes-at least in part due to the inhibition of NFKB1/p50-which indicates a chondroprotective potential of brazilin in OA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2431-2438, 2018.

Identification of pathways and genes associated with synovitis in osteoarthritis using bioinformatics analyses

Synovitis in osteoarthritis (OA) is a very common condition. However, its underlying mechanism is still not well understood. This study aimed to explore the molecular mechanisms of synovitis in OA. The gene expression profile GSE82107 (downloaded from the Gene Expression Omnibus database) included 10 synovial tissues of the OA patients and 7 synovial tissues of healthy people. Subsequently, differentially expressed gene (DEG) analysis, GO (gene ontology) enrichment analysis, pathway analysis, pathway network analysis, and gene signal network analysis were performed using Gene-Cloud of Biotechnology Information (GCBI). A total of 1,941 DEGs consisting of 1,471 upregulated genes and 470 downregulated genes were determined. Genes such as PSMG3, LRP12 MIA-RAB4B, ETHE1, SFXN1, DAZAP1, RABEP2, and C9orf16 were significantly regulated in synovitis of OA. In particular, the MAPK signalling pathway, apoptosis, and pathways in cancer played the most important roles in the pathway network. The relationships between these pathways were also analysed. Genes such as NRAS, SPHK2, FOS, CXCR4, PLD1, GNAI2, and PLA2G4F were strongly implicated in synovitis of OA. In summary, this study indicated that several molecular mechanisms were implicated in the development and progression of synovitis in OA, thus improving our understanding of OA and offering molecular targets for future therapeutic advances.